Abstract: A signal separation device is disclosed that is able to reduce a number of calculations required when separating a received signal transmitted from transmission devices into the individual transmission signal. The signal separation device includes a signal point derivation unit that multiplies the received signal with respective elements of a unitary matrix, and derives at least one received-signal signal point on a signal constellation diagram; a definition unit that defines plural sections on the signal constellation diagram, each of the sections including a predetermined number of signal points; a detection unit that detects a received-signal section from the sections, the received-signal section including the received-signal signal point; a selection unit that selects signal points in the received-signal section as candidates of the received-signal signal point; and a determination unit that determines the transmission signals based on the selected signal points.

Abstract: The object of the present invention is to prevent continued reception of unreliable information symbols at the receiver apparatus 200 in the OFDM radio communication system, so that it is possible to improve transmission quality. The radio communication system according to the present invention comprises a transmitter apparatus 100 configured to estimate conditions of propagation paths used in the radio communication, arrange information symbols along the direction of the frequency axis in accordance with a predetermined pattern based on the estimated conditions of propagation paths, and transmit a radio communication signal including the arranged information symbols and a receiver apparatus 200 configured to receive the radio communication signal, and rearrange the information symbol included in the radio communication signal along the direction of the frequency axis in accordance with a reverse pattern to the predetermined pattern.

Abstract: A channel estimation device is provided to achieve high-precision channel estimation in a MIMO or multicarrier wireless receiver. This channel estimation device is used in the wireless receiver that receives pilot signals through reception antennas. The pilot signals are modulated by a multicarrier method and are transmitted from transmission antennas. The pilot signals are orthogonal to one another. The channel estimation device includes: an estimation unit that determines a channel estimate value for each unit time slot and each unit sub carrier; and an averaging unit that averages the channel estimate values over time slots including a target time slot and sub carriers including a target sub carrier, thereby determining an average channel estimate value.

Abstract: A disclosed receiver in a MIMO multiplexing communication system, in which plural signals are simultaneously transmitted from plural transmitting antenna branches using the same frequency, and the transmitted signals are retrieved by receiving signals at plural receiving antennas, separating the received signals and searching for proper symbol metrics for each branch, comprises a QR decomposer for QR decomposing the received signals to orthogonalize the transmitted signals; a symbol replica candidate ranking unit for subtracting surviving symbol replica candidates from the QR decomposed received signals to get remaining received signals and rank the remaining signals in the increasing order of expected branch metrics of the remaining received signals; a symbol replica candidate selector for selecting symbol replica candidates in the ranked order; a branch metric calculator for calculating the branch metrics of the selected symbol replica candidates; and a threshold comparator for comparing the calculated bran

Abstract: The radio communication apparatus includes two or more antennas, a receiving unit for receiving a notice signal from a communication partner, two or more units for changing the number of data sequences and for coupling to the antennas according to two or more transmitting methods out of a MIMO multiplexing method, a MIMO diversity method, and an adaptive array antenna method, a selecting unit for selecting at least one out of the two or more units based on the notice signal, and a transmitting unit for notifying the communication partner of the transmission method corresponding to the selected unit.

Abstract: A radio communication system having a radio transmitter and a radio receiver and adopting multiple carrier modulation and code spreading modulation methods is disclosed. The radio communication system comprises a selecting unit provided in the radio transmitter or the radio receiver, for selecting an interleaving mode out of plural interleaving modes depending on radio propagation path conditions; a symbol configuration unit provided in the radio transmitter; and a symbol reconfiguration unit provided in the radio receiver. The symbol configuration unit configures information symbols to be transmitted by the radio transmitter in both time and frequency directions in a pattern according to the interleaving mode selected by the selecting unit, and the symbol reconfiguration unit reconfigures information symbols received by the radio receiver in both time and frequency directions in an inverse pattern of the pattern.

Abstract: A pilot extract section 14 extracts a pilot signal from received signal. An adder 21 in-phase adds a plurality of correlated values of pilot signals for respective subcarriers. Delay devices 201-1 to 201-6 temporarily maintain one in-phase added value. Multiplier 202-1 to 202-6 multiplies a predetermined coefficient to the in-phase added value that is output from the delay device. The predetermined coefficient reflects the result, which is obtained by correcting for multiple times the difference of channel variation in the different subcarriers that is generated when noise power per one subcarrier is calculated. Each of the multiplying results is added by an adder 24, and is squared by a square device 25. A cumulative adder 26 cumulative-adds the squared values for the whole subcarrier. A multiplier 203 averages by multiplying predetermined values to the cumulative-added values.

Abstract: A channel estimation circuit of the present invention includes: a tentative channel estimation unit for performing channel estimation by making use of a received signal and outputting the result of estimation as a tentative channel estimation signal; a noise/interference power estimation unit for estimating noise and interference power by making use of the received signal and outputting the result of estimation as a noise/interference power estimation signal; a threshold decision unit for establishing a threshold signal by making use of the noise/interference power estimation signal to output the threshold signal; and an effective path detection unit for outputting, as a channel estimation signal, paths of the tentative channel estimation signal that remains after noise paths having powers smaller than the threshold signal have been removed.

Abstract: A radio communication system having a radio transmitter and a radio receiver and adopting multiple carrier modulation and code spreading modulation methods is disclosed. The radio communication system comprises a selecting unit provided in the radio transmitter or the radio receiver, for selecting an interleaving mode out of plural interleaving modes depending on radio propagation path conditions; a symbol configuration unit provided in the radio transmitter; and a symbol reconfiguration unit provided in the radio receiver. The symbol configuration unit configures information symbols to be transmitted by the radio transmitter in both time and frequency directions in a pattern according to the interleaving mode selected by the selecting unit, and the symbol reconfiguration unit reconfigures information symbols received by the radio receiver in both time and frequency directions in an inverse pattern of the pattern.

Abstract: A corrected channel estimating apparatus is disclosed, which is capable of removing side-lobe components mutually leaking into transmission paths from channel estimates to increase the accuracy. A channel estimation unit calculates channel estimates for a plurality of transmission paths due to a signal that arrives through multipath. A channel estimate correction unit removes side-lobe components mutually leaking into the transmission paths from the channel estimates calculated by the channel estimation unit to correct the channel estimates. In this way, the corrected channel estimating apparatus estimates transmission paths of a multipath.

Abstract: The wireless base station 10 includes a multiplexing units 13 generating user data; a channel assignment control unit 14 for selecting subcarrier groups from a plurality of subcarriers on two carriers, forming two wireless frames including subchannels generated from the subcarrier groups, and time-division multiplexes and sets the user data and control data to the two wireless frames; and a transmitting and receiving unit 16 transmitting a wireless signal including the wireless frames, wherein the channel assignment control unit 14 divides all of the subchannels in the two wireless frames into areas of destination sectors, stores the control data only in the corresponding area, and stores the user data in all of the areas in the two wireless frames.

Abstract: A noise power estimation apparatus is disclosed. The noise power estimation apparatus includes: a part for calculating correlation between a received signal and a pilot signal so as to obtain a received power of the pilot signal for each path; a part for removing a multipath interference component from the received power of the pilot signal by using a predetermined power ratio between the pilot signal and a data signal so as to obtain a corrected received power of the pilot signal; a part for estimating an estimated total power of the pilot signal and the data signal included in the received signal based on the corrected received power and the predetermined power ratio; and a part for subtracting the estimated total power from a total power of the received signal so as to obtain a noise power.

Abstract: The object of the present invention is to achieve reduction of interference between cells and improvement of maximum throughput so as to improve spectrum efficiency.

Abstract: A noise power estimation apparatus is disclosed. The noise power estimation apparatus includes: a part for calculating correlation between a received signal and a pilot signal so as to obtain a received power of the pilot signal for each path; a part for removing a multipath interference component from the received power of the pilot signal by using a predetermined power ratio between the pilot signal and a data signal so as to obtain a corrected received power of the pilot signal; a part for estimating an estimated total power of the pilot signal and the data signal included in the received signal based on the corrected received power and the predetermined power ratio; and a part for subtracting the estimated total power from a total power of the received signal so as to obtain a noise power.

Abstract: A transmitter used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme includes a determination unit that determines a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission. The transmitter also includes a multiplexing unit that multiplexes a data channel with the control channel having been code-spread based on the spreading factor and the amplitude. A modulator then modulates the multiplexed signal in the OFDM scheme for transmission as OFDM symbols.

Abstract: A transmission apparatus including: a layer multiplexing unit configured to assign, to a radio resource which is divided based on a time, a frequency and a layer, a bit sequence which constitutes at least one information source to be transmitted, in accordance with a communication state and a priority level of the information source; and a layer coding unit configured to perform a layer coding processing for the bit sequence assigned to the radio resource. The layer multiplexing unit performs the assignment so that a length of each bit sequence assigned to each radio resource becomes equivalent.

Abstract: A path searcher used in a receiver includes a power delay profile generating unit configured to generate a power delay profile based on a signal received by the receiver, a sidelobe generating unit configured to identify a sidelobe component of a path contained in the power delay profile based on a response characteristic of a band-limiting filter of the receiver, a sidelobe removing unit configured to remove the sidelobe component from the power delay profile to produce a corrected power delay profile, and a path timing detection unit configured to detect a path timing based on the corrected power delay profile.

Abstract: A signal detection apparatus improving signal detection accuracy in a receiver for communications system complying with the MIMO scheme. The signal detection apparatus detects transmission signals sent from transmission antennas based on received signals received by receiving antennas. The apparatus includes: a first determination mechanism for determining symbol candidates of the transmission signals in sequence based on the QRM-MLD method using the received signals arranged in first order; a second determination mechanism for determining symbol candidates of the transmission signals in sequence based on the QRM-MLD method using the received signals arranged in second order that is different from the first order; and an output mechanism for outputting symbol candidates and likelihood of the transmission signals based on determination results of at least the first and the second determination mechanisms.

Abstract: A radio transmission system is configured to, on the occasion of radio transmission of information between a transmitter and a receiver, perform the radio transmission of information using an orthogonal frequency and code division multiplexing transmission scheme of parallelly transmitting identical information by a plurality of sub-carriers. The radio transmission system has a spreading factor variable control transmitting device for parallelly converting information channel-coded at the transmitter, according to symbols transmitted simultaneously, and for spreading a sequence of parallelized symbols in at least one of a frequency direction and a time direction by a spreading code sequence of a designated spreading factor.

Abstract: A receiving apparatus, a receiving method, and a radio communications system are disclosed. The receiving apparatus is for receiving CDMA signals transmitted by M antennas and received by N antennas, where M and N are positive integers. The receiving apparatus includes a multipath receiving signal demodulating unit for primary demodulation of the CDMA signals received by the receiving antennas to obtain estimated transmission signals, and for obtaining signals in a multipath environment of each path of the receiving antennas based on the estimated results. Further, the receiving apparatus includes a multipath interference canceling unit for deducting signals of the paths other than a target path from the signals received by the receiving antennas to obtain multipath interference cancelled signals. Further, the receiving apparatus includes a demodulator for secondary demodulation of the multipath interference cancelled signals.